1. Field of the Invention
The present invention relates to an adjustable head for a wrench. In particular, the present invention relates to a wrench including a handle and a head that can be pivotally adjusted to and retained in a desired angular position relative to the handle.
2. Description of the Related Art
FIG. 1 of the drawings illustrates a conventional wrench including a handle 4 and a head 1 that can be pivotally adjusted to a desired angular position relative to the handle 4. FIG. 2 is a top view of the head 1. A plurality of angularly spaced grooves 3 are defined in an arcuate outer surface section of a pivotal portion 2 of the head 1, and the handle 4 includes a ball 5 selectively engaged in one of the grooves 3 of the head 1. The ball 5 is apt to disengage from the respective groove 3 of the head 1 if the grooves 3 are too shallow. On the other hand, if the grooves 3 are deep for providing reliable engagement between the ball 5 and the respective groove 3, at best five (5) grooves 3 are allowed to be defined in the arcuate outer surface section of the pivotal portion 2 of the head 1. Thus, the head 1 can be located in at best five angular positions relative to the handle 4. Further, two adjacent angular positions are spaced apart from each other by thirty-six (36) degrees. As a result, use of the handle 4 in a limited space is difficult. Namely, adjustment of the angular position of the head 1 relative to the handle 4 in a limited space is difficult.
FIG. 3 of the drawings illustrate another conventional wrench including a handle 20 and a head 10 that can be pivotally adjusted to a desired angular position relative to the handle 20. FIG. 4 is a top view of the head 10, and FIG. 5 is a side view of the head 10.
The handle 20 includes a pair of lugs 21 on an end thereof, and a pin 18 is extended through aligned holes 22 in the lugs 21 and a pin hole 14 in a pivotal portion 13 of the head 10, thereby pivotally connecting the pivotal portion 13 of the head 10 to the lugs 21 of the handle 20. Teeth 15 are formed along an arcuate outer surface section of the pivotal portion 13 of the head 10 for releasably engaging with a pawl or catch 17 mounted in the end of the handle 20. Thus, the head 10 moves together with the handle 20 for driving fasteners when the catch 17 is engaged with the teeth 15 of the head 10. The head 10 can be pivoted to a desired position relative to the handle 20 when the catch 17 is disengaged from the teeth 15 of the head 10.
In this wrench, formation of the teeth 15 along an entire arcuate outer surface section of the pivotal portion 13 of the head 10 causes a reduction in the thickness of the pivotal portion 13; namely, the distance from a periphery delimiting the pin hole 14 of the head 10 to the dedendum circle of the pivotal portion 13 of the head 10 is “L”. As illustrated in FIG. 3, the pivotal portion 13 of the head 10 is subjected to a torque at sections 14a and 14b when the wrench is turned clockwise for driving a fastener. Cracks 16 are apt to be generated in the torque-bearing section 14bwhen the handle 20 is turned clockwise. The torque-bearing section 14bis damaged when the torque applied to the wrench is relatively large. Similarly, the pivotal portion 13 of the head 10 is subjected to a torque at sections 14c and 14d when the wrench is turned counterclockwise for driving a fastener. Cracks 16 are apt to be generated in the torque-bearing section 14d when the handle 20 is turned counterclockwise, as illustrated in FIG. 6. The device for retaining the head in a desired angular position relative to the handle sacrifices the torque-bearing capacity of the wrench.